Step 1 Synthesis of tert-butyl 2-bromopropionate. Isobutene (2.4 g, 42.8 mmol) was condensed into a pressurized reaction flask at -15 °C. Dioxane (6 mL) and 2-bromopropionic acid (3.5 mL, 38.9 mmol) were then added and the mixture was stirred for 5 minutes. After slow warming to -10°C, concentrated sulfuric acid (250 μL) was added dropwise. The reaction vial was sealed and the reaction mixture was stirred at room temperature overnight. After the reaction was completed, the reaction vial was opened and the reaction mixture was poured into dichloromethane (50 mL). The organic phase was washed sequentially with 20% potassium carbonate solution (50 mL) and water (50 mL), dried over anhydrous magnesium sulfate, and concentrated under reduced pressure to give tert-butyl 2-bromopropionate (2.17 g, 27% yield). The product was characterized by 1H NMR (CDCl3, δ): 4.31 (1H, q, J=7.1Hz), 1.81 (3H, d, J=7.1Hz), 1.52 (9H, s).
